Chicago saw its deadliest holiday weekend after a total of 65 people were shot, including 13 killed, according to ABC News.

The violence reached a fever pitch on Labor Day, when 31 people were shot between 6 a.m. on Monday and 3 a.m. Tuesday, The Chicago Tribune reports. Police attribute a majority of the uptick to retaliatory acts carried out by local gangs.

Among the injured was a nine-months pregnant woman who was shot in the abdomen. The woman delivered a nearly full-term baby in a local hospital. She was listed in critical condition, according to ABC News; her baby’s condition was not released.

Eddie Johnson, Chicago’s top cop, spoke to a group of reporters once news of the tally broke.

“It’s not a police issue, it’s a society issue,” Johnson said. “Impoverished neighborhoods, people without hope do these kinds of things…You show me a man that doesn’t have hope, I’ll show you one that’s willing to pick up a gun and do anything with it.”

Johnson pointed to an increase in gun arrests from last year, including more than 6,000 illegal gun recoveries. He also acknowledged the controversy surrounding the Laquan McDonald shooting and subsequent investigation, which added another layer of distrust between Chicago’s Black community and the police.

The Tribune writes:

“Homicides in Chicago this year have risen to levels not seen since the 1990s, when killings peaked at more than 900 annually. The 90 homicides in August tied for the most the city had seen in a single month since June 1996. In the worst previous month — July 1993 — 99 people were slain.”

So far in 2016, there have been 2,346shooting incidents, up a little more than 47 percent from 1,594 in 2015, writes the news outlet.

The gun violence has not engulfed the entire Chicago metropolitan area and is concentrated within five police districts on the South and West sides, where an increasing number of innocent bystanders are being caught in the crossfire in gun battles between rival gangs.

Police Superintendent Eddie Johnson told the Tribune that officers are working to stem the violence, seizing 6,000 illegal guns so far this year.

“And I’ll tell you this, it’s frustrating for them to arrest a guy on Friday for an illegal gun and then next Thursday they see this guy right back out on the street with another illegal gun,” he told the Tribune.